Photodegradation of Oxytetracycline Using Tb-doped TiO2 Prepared by Liquid Phase Plasma Method

TiO₂ possesses properties such as chemical stability, high photocatalytic activity, redox capability, and non-toxicity, making it widely utilized in various environmental applications, including wastewater photocatalytic decomposition, sterilization, and air purification. However, TiO₂ exhibits a high band gap energy and suffers from electron-hole recombination, which reduces its photocatalytic efficiency. Additionally, its photocatalytic activity is limited to the UV region, which constitutes only 5∼7% of sunlight. An effective approach to overcome these limitations is doping TiO₂ with dopants such as metals, non-metals, rare earth elements, and noble metals. In this study, terbium (Tb), a rare earth element, was doped into TiO₂ to enhance light absorption in the visible region, reduce band gap energy, and achieve efficient electron-hole pair separation. The photocatalytic activity was evaluated under UV LED and blue LED light sources using oxytetracycline (OTC) as the target pollutant. Tb-doped TiO₂ was synthesized using the Liquid-phase Plasma Process (LPP). The fabricated photocatalyst demonstrated improved OTC degradation efficiency. Tb was uniformly distributed on the TiO₂ surface, and the band gap energy was reduced from 3.15 eV to as low as 2.90 eV. As a result of performing a decomposition experiment targeting the antibiotic OTC, the decomposition reaction rate constant k was improved up to 3.5 times under blue LED conditions. In addition, the optimal Tb doping content was confirmed to be 2 mM through the decomposition experiment results and characteristic analysis of Tb-doped TiO₂. Through this study, it is expected that Tb-doped TiO₂ manufactured through the LPP process is used in the visible light range and can be utilized in advanced oxidation process technologies such as difficult-to-decompose antibiotics.